Machine for grinding gears



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MACHINE FOR GRINDING GEARS Filed Dec. 29, 1950 5 Sheets-Sheet l INVENTOR 17'66561'56 K/i Ward ATTORNEYS Oct. 16, 1934. F. A. WARD MACHINE FOR GRINDING GEARS Filed Dec. 29, 1950 5 Sheets-Sheet 2 @ch 16 1934. F, A, WARD MACHINE FOR GRINDING GEARS Filed Dec.

5 Sheets-Sheet 3 wrmm A W Oct 16, W34. F. A, WARD MACHINE FOR GRINDING GEARS 5 sheets-sheet 4 Filed Do. 29, 1950 ATTORNEYS Oct. 16, 1934. F. A. WARD MACHINE FOR GRINDING GEARS 1930 5 Sheets-Sheet 5 Filed Dec. 29

INVENTOR fl''aierz'c/V/i. W'arci ATTO RN EY,S

Patented Oct. 16, 1934 UNITED STATES PATENT OFFICE Frederick A. Ward, Detroit, Mich., assignor to The Gear Grinding Machine Company, Detroit, Mich a corporation of Michigan Application December 29, 1930, Serial No. 505,378

Claims. (01. 51-95) The invention relates to machines for grinding gears having helical or otherwise curved teeth, being more particularly adapted for grinding helical spur gears and worms. It is the primary object o of the invention to accomplish this result by the use of a formed grinder wheel. It is a further object to obtain a construction which will insure a high degree of accuracy, first, as to the contour of each individual tooth surface; second, in indexing from one tooth to another and third, in the form and angle of the helical curve. Still further it is an object to provide for quickly adjusting the machine for the performance of work difiering in specific form. With these and other objects in view the invention consists in the construction as hereinafter set forth.

In the drawings:

Figure l is a side elevation of the machine;

Figure 2 is a top plan view thereof;

Figure 3 is a longitudinal section partly in elevation in the vertical plane of the axis of the work;

Figure 4 is a cross section on line 4-4 of Figure 3;

Figure 5 is a cross section on line 5--5 of Fig- 25 ure 3;

Figure 5A is a sectional elevation of the parts shown in Figure 5 viewed from the opposite side;

Figure 6 is a cross section on line 6-6 of Figure 3;

Figure 7 is an elevation of one of the exchangeable patterns;

Figure 8 is a diagrammatic perspective view showing the general arrangement of the hydraulic system;

Figure 9 is an enlarged horizontal section through a portion of the valve controlling mechamsm;

Figure 10 is a vertical section therethrough;

Figure 11 is a sectional elevation showing a modified construction.

Broadly described, my improved machine comprises a frame having a formed grinder wheel mounted thereon, a work holder mounted for adjustment into a predetermined angular relation to said grinder wheel, and means for simultaneously imparting to said work holder an axial and a rotative movement such as to maintain the formed cross section of the grinder in the same relation to each portion of the tooth surface successively ground thereby. The machine is further provided with an index mechanism for advancing successive teeth into operative relation to the grinder wheel and a trimmer mechanism through which the correct cross sectional contour of the grinder is restored from time to time.

In detail, A is the bed or frame of the machine; B is a carriage mounted for reciprocation upon said bed and upon which the work is mounted; C is a column extending upward from the bed and D is the grinder wheel which is mounted for vertical adjustment upon the column C. E is a trimming mechanism mounted upon the carriage B so that it can be periodically carried thereby into operative relation to the grinder wheel to retrim the same to the desired contour. The parts thus far described are the same in construction as in many machines heretofore used, and are not an essential part of the present invention.

Mounted upon the carriage B is a segmental horizontal base plate F for an angularly adjustable work supporting frame G. The frame G is pivoted to the plate F by a pin G having a vertical axis which in the normal position of the parts extends upward through the center of the grinder wheel D perpendicularly to and intersecting the axis thereof. The frame G is adjustably secured to the plate F in different positions by suitable means such as the clamping bolts (3* passing through slots G therein and engaging threaded apertures F in the plate F. A series of these apertures F is arranged so that the frame G may be swung about the pin G through the maximum angle required for variations in the spiral pitch of the gears to be ground. It is, however, desirable to limit the angular adjustment of any particular machine so that the actuating mechanism, which will hereinafter be explained, lies outside of the angle of friction.

The frame G has mounted thereon the axially aligned bearings .I H for a rotary and axially movable cylindrical work holder I. The forward end of this work holder I has a socket I for receiving the work which as specifically shown is a spiral spur gear wheel I having a shank or shaft 1 engaging the socket. The rear end of the work holder I has a portion I reduced in diameter forming a mounting for exchangeable pattern sleeves J. Each of these sleeves J is formed with one or more helical grooves J therein, preferably three of such grooves arranged at equal angles to each other around the periphery of the sleeve. The helical grooves are engaged by pin bearings K which are mounted in a sleeve K surrounding the members I and J and intermediate the same and the bearing H. The pins K are wedge shaped to fit a corresponding tapered cross section in the helical groove J and springs K force these pins radially inward so as to automatically take up .any lost motion. Thus assuming that the sleeve K is held stationary and bracket L projecting rearward from the frame G. In this cylinder is a piston L provided with a piston rod L connected to the rear end of the member I by the swivel coupling L which permits independent rotation of said member L.

The exchangeable sleeve J is adjustably coupled for rotation with the member I through the medium of a member M clamped to the rear end portion of said sleeve and having a laterally projecting pin M' engaging a bifurcated member M? which is clamped to the shank I of the member I.

Admission of fluid to the hydraulic cylinder L is controlled by a valve N which is automatically reversed as the piston L approaches the opposite ends of its movement by mechanism of the following construction.

Arranged parallel to the piston rod L is a rod 0 slidable in bearings O and having secured thereto the collar 0 which has spaced lugs O projecting laterally therefrom.- N is a rockable lever pivoted in a bearing N in axial alignment with a rock shaft W which operates the valve N. The lever N has a pin N extending into the path of the lugs 0 so that when the rod 0 is moved longitudinally one or the other of said lugs 0 will contact with the pin N to rock the lever N. A

the lever is actuated by the movement of the rod 0 it will first take up the lost motion between the lever and the rock shaft N and will then quickly rock said shaft by the actuation of the spring N The rod 0 is actuated by the piston rod L by means which as shown comprises a disk 0 clamped between the sleeve J and the member M which extends between spaced lugs Q on the rod 0. The arrangement is such that the lost motion between the disk and the lugs 0 will permit the greater part of the travel of the piston L but as said piston approaches the end of its movement towards either end of the cylinder it will contact with one or the other of the lugs O actuating the rod 0 and through the connecting mechanism just described reversing the valve N. The valve N is connected by conduits N and N to opposite ends of the cylinder L and the arrangement is such that in one position of said valve pressure fluid is admitted through the conduit N to one end of the cylinder, and an exhaust is also connected through the conduit N to the opposite end of the cylinder. while upon the reversal of the valve the pressure fluid is connected to the conduit N and the exhaust to the conduit N Consequently the function of the complete mechanism is to reciprocate the piston L in the cylinder L. automatically reversing the movement after it reaches the ends of the cylinder.

with the mechanism as thus far described it will be apparent that the'work such as aspiral spur gear I carried by the member I will be simultaneously axially reciprocated and revolved in relation to the grinder wheel so as to produce a generating grinding of a tooth surface. Where the gear isprovided with a series of teeth, it is necessary to rotatively index the work so as to produce corresponding developing grinding movements with respect to the successive teeth. This isaccomplished by mechanism of the following construction.

The sleeve K which surrounds the member I and pattern sleeve J has mounted thereon an index plate P having a series of peripheral V- shaped notches P therein. P is a V-shaped detent for engaging the-notches P, this detent being mounted on 'a rock arm P pivoted at P Adjacent and parallel to the index plate P is a member Q which has a hub portion Q mounted for rotation upon the sleeve K. It is also provided with a peripheral gear segment Q which is in mesh with a rack R formed on the central portion of a double ended piston R engaging a cylinder R which extends transversely of the machine. The cylinder R has adjustable stops R at opposite ends thereof for exactly limiting the travel of the piston so that when the piston is reciprocated by fluid admitted alternately to opposite ends thereof it will impart an oscillatory movement to the gear segment Q and the member Q bearing the same. The member Q is further provided with a cam Q which engages a roller P on the rock arm P to lift said rock arm and thereby to disengage the detent P from the notch P. Q is a pawl also carried by the member Q which engages a ratchet ring P on the side of the index plates P and during one phase of the oscillatory movement will rotate said plate an exactly predetermined amount. Thus where fluid under pressure is alternately introduced at opposite ends of the cylinder R. the piston R will be reciprocated to oscillate the member Q, first disengaging the detent P from the index wheel by the operation of the cam Q engaging a roller P and also moving the pawl Q to slip over the teeth of the ratchet ringv P and then during the reverse oscillation moving the index plate and finally locking the same by re-engagement of the detent P.

It is necessary to effect this indexing during.

the interval when the work has moved axially out of engagement with the grinder wheel D and before returning into engagement therewith. This is accomplished and properly timed by mechanism constructed as follows:

In alignment with the rod 0 is a valve casing S containing a piston valve S which has a stem S extending towards the rod 0. The end of the stem S is partly cut away as indicated at S and the reduced portion engages a socket S at the adjacent end of the rod 0. Within this socket is a rockable member S which in one position will contact with the reduced end of the member S so as to move the same in an axial direction. If, however, the member S is rocked into a different position it will clear the reduced end of the member S so as to permit a telescopic movement of said member with the socket S A spring S within the cylinder S actuates the piston in a direction counter to that imparted by the rod 0. S is a rock arm for rotating the member S being actuated in one direction by a spring S and in the opposite direction by engaging a stop S on the cylinder S. The arrangement of the parts is such that when the be actuated to admit fluid under pressure to the rod 0 is moved in an outward direction by the disk 0 engaging the lug 0 the member S will bear against the reduced end of the stem S and will actuate the'valve S against the tension of the spring S As soon, however, as the rock arm S engages the stop S the member S will be rocked to disengagement from the reduced end of the stem S entering the cut away portion S whereupon the tension of the spring S will instantaneously return the valve S to its normal position.

The valve S controls a hydraulic motor comprising a cylinder T connected by a conduit T with the valve casing S and-containing a piston 'I' which is actuated in one direction by the fluid entering through said conduit. A spring T in the cylinder T returns the piston T to its normal position as soon as the valve S has been returned, thereby connecting the conduit T with the exhaust. A rod T connected with the piston 'I engages a rock arm U which rocks the stem U of a valve U This valve controls the cylinder B. being connected with the opposite ends thereof through the conduits W and U, the construction being such that in the normal position of the valve S pressure fluid will be in the conduit U and the exhaust connected with the conduit U while in the reverse position of said valve S the conduit U will be connected to the pressure fluid and the conduit U with the exhaust.

Complete operation then placed in engagement with the work holder I I and adjusted intoproper registration with the grinder wheel. This adjustment can be effected by loosening one of the clamps M M which permits rotation of the sleeve J with respect to the member I until proper registration is secured. The sleeve J is also selected to correspond to the particular gear. The trimming of the grinder wheel is effected by the trimmer E with which the wheel is engaged by movement of the table B, but as this trimming mechanism forms no part of the present invention it will not be described'in detail.

Movement is imparted to the work by the opening of the valve V which admits fluid under pressure to each of the valves N, S and U The valve N will first admit pressure fluid to the outer end of the cylinder L through the conduit N and will connect the conduit N from the opposite end of said cylinder to the exhaust. This will move the piston L forward carrying with it the member I which through its connection with'the sleeve J and the engagement of helical grooves in the latter with the pins J. will be given a simultaneous axial and rotative movement, carrying the gear I past the grinder wheel D. Near the completion of this movement the disk 0 contacts with one of the lugs O ,thereby moving therod 0 and through the lug 0 and pin N rocking the lever N until the spring N completes the rocking movement with a snap. This will instantaneously reverse the valve N, admitting pressure fluid to the conduit N and connecting the conduit N cylinder T. This will actuate the piston 'I in said cylinder and through the rod T will rock the arm U and shaft U of the valve U so as to admit fluid under pressure into the conduit U to one end of the cylinder R and to thereby move the piston R in said cylinder. The time interval during which the valve S admits pressure fluid to,

the cylinder T is very short, as the further movement of the rod Obrings the rock arm S into contact with the stop S releasing the stem S and permitting the stem S to quickly reverse the valve. Consequently the piston R is also quickly reversed and the completion of the oscillatory movement of the member Q is within the short time interval that the work is out of engagement with the grinder wheel. As previously described in detail, the oscillation of the member Q eifects indexing movement of the sleeve K so that before the grinder re-engages with the work a succeeding tooth is brought into operative relation thereto. This completes the cycle which is successively repeated until all of the teeth of the gear have been ground. The work then can be removed and a new blank engaged with the holder I and adjusted and then ground in a similar manner.

It will of course be-understood that the grinder wheel is trimmed as frequently as necessary to maintain its proper cross sectional contour. This can be done at any time by a movement of the table B which is eflected by manually controlled means (not shown) It will be further understood that the contour to which the grinder wheel is trimmed is one which will develop the correct contour in the helical tooth, although not necessarily exactly thesame in form: Thus due to the angle at which the grinder wheel is set relative to the axis of the gear or worm, the contact between the grinder wheel and the work will not be in the axial plane ofthe grinder so that it is necessary to trim the wheel to a slightly diflerent form from that which is developed in the tooth ground.

The use of hydraulic motors for actuating different parts of the mechanism has an additional advantage that it does not interfere with the adjustment of the frame G to diiferent angular positions corresponding to the helical angle of the work to be ground. Thus by the use of flexible conduits for the pressure and exhaust connections, the frame G can be readily adjusted without changing the operation of the hydraulic mechanism.

While I have specifically described a construction designed for the grinding of helical spur gears in which the helical angle is such as to permit of actuating the work holder by axial pressure applied thereto, it is to be understood that my inpitch of the helix is such as to lie within the angle of friction or pressures applied axially thereof, it is necessary to impart to the work holder a rotative movement. In- Figure 11 such a construction is diagrammatically shown in which W is the spindle for rotating the work W and which has the helical pattern guide W mounted thereon. W is a gear wheel on the spindle which is in mesh with a long driving gear W.- W is a stationary nut for engaging the helical pattern guide. With this construction rotary movement is directly imparted to the spindle W by the long gear wheel W driving the gear wheel W while the pattern W in cooperation with the stationary nut W causes the axial movement. The conthat previously described.

What I claim as my invention is:

1. In a machine for grinding spiral gears, the combination with a frame a rotary arbor mounted thereon, a formed grinder wheel on said arbor, a table mounted on said frame to be pivotally adjustable about an axis perpendicular thereto intersecting the axis of said arbor and passing centrally through said formed grinder wheel, a

work holder for the gear to be ground including a spindle capable of axial and rotary movements, an exchangeable sleeve surrounding and secured to said spindle and provided with a helical pattern guide, a surrounding bearing for supporting said spindle and sleeve mounted on said table, means for imparting to said spindle one of said movements and means cooperating with said helical pattern guide to produce in said spindle the other of said movements.

2. In a machine for grinding spiral g ears, the combination with a frame, of a rotary arbor mounted thereon, a formed grinder wheel on said arbor, a table mounted on said frame to be pivotally adjustable about an axis perpendicular thereto intersecting the axis of said arbor and passing centrally through said formed grinder wheel, a work holder including a spindle capable of axial and rotary movements, an exchangeable sleeve surrounding and secured to said spindle and provided witha helical pattern guide, a surrounding bearingfor supporting said pattern and sleeve mounted on said table, means for imparting to said spindle one of said movements, a member cooperating with said helical pattern guide to develop in said spindle the other of said movements, and means for indexing said cooperating member angularly about the axis'of said spindle and helical pattern.

3. In a machine for grinding spiral gears, the combination with a frame, of a rotary arbor mounted thereon, a formed grinder wheel on said arbor, a table mounted on said frame to be pivotally adjustable about an axis perpendicular.

thereto, intersecting the axis of said arbor and passing centrally through said formed grinder wheel, a work holder for the gear to be ground, a bearing mounted on said table in which said work holder is supported permitting axial and rotative movement therein, an exchangeable pattern sleeved upon and secured to said work holder within said bearing and provided with one or more helical guides of a predetermined pitch,

a member surrounding said pattern within said bearing and engaging said helical guide, index mechanism for periodically rotatively adjusting the latter member and for locking the same in each position of adjustment and means operating when-said member is locked for imparting to said work holder an axial movement whereby a helical movement corresponding to said pattern is developed therein.

4. In a machine for grinding spiral gears, the combination with a frame, of a rotary arbor mounted thereon, a formed grinder wheel on said arbor, a table mounted on said frame to be pivotally adjustable about an axis perpendicular thereto, intersecting the axis 'of said arbor and passing centrally through said formed grinder wheel, a work holder mounted on said table, an indexing mechanism therefor, reciprocating hydraulic motors for respectively actuating said work holder and index mechanism, valves controlling said motors, means operated by the reciprocation of said work holder for reversing the valve of the work reciprocating motor at opposite ends of the stroke thereof, and for double reversing the valve for the indexing motor at one end of said stroke whereby the index mechanism is quickly and completely actuated at one end of the work stroke. 7

5. In a machine for grinding spiral gears, the combination with a frame, of a rotary arbor mounted thereon, a formed grinder wheel on said arbor, a tablemounted on said frame to be pivotally adiustable about an axis perpendicular thereto, intersecting the axis of said arbor and passing centrally through said formed grinder wheel, a work holder mounted on said table, an indexing mechanism therefor, reciprocating hydraulic motors for respectively actuating said work holder and indexing mechanism, valves for said motors, a valve actuated reciprocating rod, a lost motion connection between the reciprocating work holder and said valve actuating rod whereby the latter is actuated oppositely at opposite ends of the work stroke, means actuated by said valve rod for reversing the valve of the work reciprocating motor at opposite ends of its stroke, means also actuated by said valve rod for reversing the indexing mechanism motor at one end of the stroke of said rod, 9, spring for reversing the latter valve and'a trip'mechanism actuated at the completion of the stroke of said rod for releasing said latter valve to be reversed by said spring.

FREDERICK A. WARD. 

